1. Field of the Invention
The present invention relates to an electronic component. More specifically, the present invention relates to an electronic component that converts an unbalanced signal into a balanced signal.
2. Description of the Related Art
As electronic components according to related art, for example, a multilayer balance filter described in Japanese Patent No. 4525864 is known. Hereinafter, the multilayer balance filter described in Japanese Patent No. 4525864 will be described with reference to the drawings. FIG. 15 is an equivalent circuit diagram of a multilayer balance filter 500 described in Japanese Patent No. 4525864. FIG. 16 is a perspective view of the outward appearance of the multilayer balance filter 500 described in Japanese Patent No. 4525864. FIG. 17 is an exploded perspective view of the multilayer balance filter described in Japanese Patent No. 4525864.
As illustrated in FIG. 15, as its circuit configuration, the multilayer balance filter 500 includes coils L11 and L12, capacitors C11 to C13, an input port P11, and output ports P12 and P13. The coil L11 and the capacitor C11 form an LC parallel resonator. The coil L11 and the coil L12 are electromagnetically coupled to each other. The input port P11 is connected to the coil L11, and the output ports P12 and P13 are connected to the coil L12. The capacitors C12 and C13 are connected between the coil L12, and the output ports P12 and P13, respectively, and are grounded. In the multilayer balance filter 500 mentioned above, an unbalanced signal is inputted from the input port P11, and balanced signals are outputted from the output ports P12 and P13.
As illustrated in FIGS. 16 and 17, the multilayer balance filter 500 mentioned above is formed by a laminated electronic component. More specifically, the multilayer balance filter 500 includes a laminate 508, outer electrodes 509 (509a to 509f), linear electrodes 512 (512a to 512d), capacitor electrodes 514 (514a to 514d), and via hole conductors V101 to V105.
As illustrated in FIG. 17, the laminate 508 includes insulator layers 510a to 510f that are laminated so as to be arranged in this order from the upper side to the lower side of the laminating direction. The outer electrodes 509a to 509c are provided on one side surface of the laminate 508, and the outer electrodes 509d to 509f are provided on the other side surface of the laminate 508. The outer electrode 509a is the input port P11, and the outer electrodes 509d and 509f are the output ports P12 and P13, respectively.
The capacitor C11 includes capacitor electrodes 514a and 514b. The coil L11 includes the linear conductor 512b and the via hole conductors V103 to V105 that are connected in series. The coil L12 includes linear conductors 512a, 512c, and 512d and the via hole conductors V101 and V102 which are connected in series. The capacitor C12 includes the capacitor electrodes 514b and 514c. The capacitor C13 includes the capacitor electrodes 514b and 514d. 
When the multilayer balance filter 500 configured as mentioned above is mounted onto a circuit board, the lower surface of the laminate 508 is opposed to the circuit board. That is, the lower surface of the laminate 508 serves as a mounting surface.
Incidentally, the multilayer balance filter 500 described in Japanese Patent No. 4525864 functions as a band pass filter that passes high-frequency signals within a predetermined band. However, the multilayer balance filter 500 has a problem in that high-frequency signals with frequencies higher than the predetermined band are outputted from the output ports P12 and P13.
More specifically, the mounting surface of the multilayer balance filter 500 is the lower surface of the laminate 508. Therefore, the coil L11 and the capacitor C11 are connected to the circuit board via the outer electrode 509e provided on a side surface of the laminate 508. Consequently, an electric current path formed by the outer electrode 509e extending in the laminating direction is formed between each of the coil L11 and the capacitor C11, and the circuit board. A parasitic inductance is created in such an electric current path. Since a parasitic inductance blocks high-frequency signals with high frequencies from passing through, the parasitic inductance blocks high-frequency signals with frequencies higher than a predetermined band from flowing to the ground side. As a result, high-frequency signals having frequencies higher than the predetermined band are not removed, leading to deterioration of the out-of-band attenuation characteristics of the multilayer balance filter at frequencies higher than the predetermined band.